A caller identification system provides a calling party's telephone number and/or other identifying information to the called party before answering a phone call. More particularly, a display at the called telephone provides the calling party's telephone number and/or other identifying information while the called party's telephone is ringing. Accordingly, the called party can decide whether or not to answer the phone call based on the identification of the calling party.
If the called party does not recognize the calling party, the called party may choose to not answer the call. Similarly, if a caller identification system is unable provide identifying information for the call, the called party may choose to not answer the call.
When a call is placed from a cellular radiotelephone, a caller identification system may not always be able to provide the telephone number and/or other identifying information for the calling cellular radiotelephone. More particularly, when a call is placed from a cellular radiotelephone outside its home network area (i.e. while roaming), a caller identification system may not always be able to provide the telephone number for the calling cellular radiotelephone at the called telephone.
For example, a host cellular network (other than the home network for the cellular radiotelephone) handling the call from the roaming cellular radiotelephone may not have access to sufficient information to identify the roaming cellular radiotelephone by telephone number. When a roaming cellular radiotelephone places a call, the host cellular network (other than the home cellular network for the radiotelephone) may only be provided with the electronic serial number (ESN) of the roaming cellular radiotelephone, which is used for billing purposes. As will be understood, the ESN is a unique number permanently assigned to a cellular radiotelephone when the radiotelephone is manufactured, and the ESN is permanently stored in Read Only Memory (ROM) of the cellular radiotelephone. Because the ESN is assigned to a radiotelephone when the radiotelephone is manufactured before a telephone number can be assigned to the radiotelephone, the ESN and the telephone number are different.
Desired calls from roaming cellular radiotelephones may thus be missed when the caller identification system fails to identify the source of the call so that the called party believes the call is from an unknown source. For example, a first family member may have an automobile breakdown in an area outside the home cellular network, and the first family member may place a cellular radiotelephone call home for assistance while roaming. Because the caller identification system fails to identify the source of the call, a second family member at home may decide to not answer the call believing the call to be from a stranger. Accordingly, the first family member may be unable to obtain timely assistance from home.